1. FIELD OF THE INVENTION
This invention relates generally to a shaft coupling and, more particularly, to a coupling for connecting the ends of two coaxial shafts positioned within a third shaft so that relative rotation between the coaxial shafts and the third shaft is permitted.
2. DESCRIPTION OF THE PRIOR ART
While this invention may be employed in many fields, it is particularly useful in conjunction with drive train assemblies for heavy-duty earthmoving equipment, such as crawler tractors or other tracked vehicles.
Presently, the drive train of such a vehicle includes an engine, a torque converter powered by the engine and a gear assembly driven by the torque converter through a transmission. The gear assembly rotates a drive axle which carries a drive sprocket engaging the endless track to effect travel thereof. Typically, the aforementioned components are arranged in series with the engine located at the forward end and the drive axle located at the rearward end of the vehicle. However, it has been found that such an arrangement is not always possible or necessary. For example, the transmission might be positioned rearwardly of the drive axle with the transmission input shaft extending rearwardly from the torque converter past the drive axle and the transmission output shaft extending forwardly to drive the connecting gears which rotate the drive axle.
In some situations, the available space within the vehicle is limited and the use thereof critical. In order to reduce the amount of required space for the drive train, the transmission is constructed so that the input and output shafts extend from the transmission in one direction and are concentrically arranged, the output shaft being disposed about the input shaft.
Usually, the transmission, the gear assembly and the drive axle are sealed within a suitable housing filled with lubricating fluid. A long input shaft extends between the torque converter and the transmission and an output shaft, through which the input shaft extends, drives an output sleeve or gear to rotate the drive axle. However, the utilization of the long input shaft renders servicing of this portion of the drive train, particularly, the transmission and the interconnecting shafts, somewhat difficult. First, the input shaft can only be disconnected from the other components with difficulty and, second, the long shaft, particularly in large vehicles, is extremely heavy which does not permit facile handling thereof.